1. Field of the Invention
The present invention relates to an electrostatic latent image forming medium, an image forming apparatus, and a method of forming an electrostatic latent image. More particularly, the present invention relates to an electrostatic latent image forming medium that forms an electrostatic latent image by controlling electrodes under an imaging surface, e.g. using an array of thin film transistors (TFTs), an image forming apparatus transferring a desired image from the electrostatic latent image, and a method of forming the image.
2. Description of the Related Art
In general, an electrophotographic image forming apparatus, e.g., a copier, a laser printer, or a facsimile, prints an image by forming an electrostatic latent image on a photosensitive medium, e.g., a photosensitive drum or a photosensitive belt, using a laser scanning unit (LSU), developing the electrostatic latent image using a developing agent having a predetermined color, and transferring the developed image onto a tangible medium, e.g., a sheet of paper.
FIG. 1 illustrates a schematic view of a conventional electrophotographic image forming apparatus including an LSU 10, a photosensitive drum 20 on which an electrostatic latent image is formed by the LSU 10 scanning a laser beam onto a surface thereof, and a toner supplying roller 30 supplying toner to the electrostatic latent image formed on the surface of the photosensitive drum 20.
The LSU 10 includes a laser diode (LD) 11 emitting a laser beam, a polygonal mirror 12 scanning the laser beam emitted from the LD 11, a focusing lens 13 focusing the laser beam reflected by the polygonal mirror 12, and a mirror 14 reflecting the laser beam that passed through the focusing lens 13 to form an electrostatic latent image on the surface of the photosensitive drum 20.
When the LSU 10 scans a laser beam onto the surface of the photosensitive drum 20 charged with a predetermined potential, electric charges in a portion of the surface of the photosensitive drum 20 onto which the laser beam is scanned disappear. Therefore, an electrostatic latent image with a potential different from potentials of other portions of the surface of the photosensitive drum 20 is formed in the portion onto which the laser beam is scanned. Toner supplied by the toner supplying roller 30 is selectively adhered to the electrostatic latent image by an electrostatic force. Thus, the electrostatic latent image develops into a desired image. The developed image on the surface of the photosensitive drum 20 is transferred to a sheet of print paper P, and then fixed on the sheet of print paper P by a fixing unit (not shown).
Since the LSU 10 has a complicated structure, the use thereof increases the size and manufacturing cost of the conventional image forming apparatus. In addition, since the LSU 10 scans a laser beam while the polygonal mirror 12 is rotated by a motor (not shown), it is difficult to increase a printing speed by reducing the time needed for scanning the laser beam.